The interview process was frictionless.

The interview was well-structured, with each round focusing on one aspect/evaluation criterion at a time, which I find often missing in company interviews.

The panel helped in thinking through the problem in case they thought I was getting stuck.

Overall, it was a great experience. I very much enjoyed interacting with the panel.

Determine the frequency of all elements ranging between 1-N in an array of size M, such that M > N, without using extra space.

The queries for retrieving frequency should be answered in O(1), and the algorithm should run in O(M).